The present invention relates to error detection, and more particularly, this invention relates hierarchical control of tiered error recovery for tape storage device.
Error detection and recovery is important to any system in which data passes from one point to another. Error detection and recovery is particularly important in the data storage industries, as users rely on the integrity of the stored data for everything from day to day operation to long term archiving. Tape drives require inline error recovery algorithms to recover errors during data processing.
In a field or test environment implementing a tape-based data storage system, situations may arise where successful inline recovery may still impact overall performance, as in the case of frequent error recovery known as an error burst. Error bursts, which may include a large number of errors in a given time frame or in a given length of tape in a given direction, are not easily identified since no permanent errors occur and data continues to transfer across the host/drive interface. Even if individual recovery is only transitory in nature, when it persists over long stretches of tape, these error bursts can lead to host command timeouts and excessive processing times that seriously degrade performance.
In order to enhance basic inline recovery, a tiered error recovery architecture performed by microcode may be used. Recovery tiers are delineated by context, scope, and functionality. Each tier uses different strategies and applies persistence methods in an effort to improve the error rate. However, since each tier has a different context and scope, their respective persistence methods can come into conflict, which causes recovery issues that must be dealt with.